Slowly but surely, bit by bit, I'm going to invite you to make your your way through my field experience in Tanzania, wherein I teamed up with an amazing bunch of individuals to find out where the bats fly to.

Every evening come dusk (or a little before, truth be told), Eidolon helvum, also know as the straw-colored fruit bats, start swarming above their tree roosts like bees, imagine if you will, but bigger and spread higher and wider across the sky. They circle above you for what seems like an eternity, and then just as you start questioning the wisdom of standing under hundreds of flying bats (and their droppings, but that's when PPE comes into play right?), they spread out and make their way towards lands unknown for yet another night of foraging. No one knows where they are going, just that they go somewhere. No one who sees bats flying around knows where they are coming from, just that they come from somewhere. That's where we stepped in, and decided to unearth us some bat traveling secrets.

And so, the Bat Diaries will chronicle my journey to Morogoro, Udekwa, and Illovo, three vastly different places in Tanzania united by the warmth of the local people, beautiful landscapes, and delicious ugali. Three places where the VISHA team braves the elements of the capricous seasons, to sample bats so we know more about what viruses they're shedding, and when they're more likely to shed them. Except this time, I was lucky enough to tag along with the team, and get to do some bat tracking!

Photo by Nistara Randhawa

Did I mention only straw-colored fruit bats above? Well, we also sampled the Egyptian fruit bat (Rousettus aegyptiacus), like the adorable mom bat pictured here.

The bat cave. A dark, mysterious abyss and portal to another world beyond the reach of the sun where minerals grow and the floor and ceiling are alive with sound and movement. Caves are fascinating, holding the promise of discovery, and not just for adventurers and spelunkers.

Recently, disease ecologists have been exploring caves for viral discovery, sampling cave-dwelling bats to learn more about their viro-diversity as well as their potential to act as reservoirs for dangerous diseases like Ebola and Marburg virus. At Python Cave in Uganda where tourists acquired Marburg virus infection, for example, a team from the CDC sampled a large population of fruit bats suspected as hosts. They detected Marburg, and learned a lot about the dynamics of viral shedding among bats in the colony to better understand risks for exposure and infection.

This month HALI's own "Team Popo" (the Bat Team) ventured into the Udzungwa mountains to do some cave explorations of our own as part of the Viral Sharing (VISHA) project. Led by Dr. Popo himself (Zikankuba Sijali), the team geared up and headed off to the Magombelema Cave, a new site where they first worked to characterize the area and learn from people in the communities about their interactions with bats and other wildlife.

Wearing Tyvek suits with hoods, googles, and N-95 respirators to protect themselves from exposure to any potentially dangerous pathogens, Team Popo navigated through Magombelema's chambers and identified some great locations to place mist nets. Bats were safely captured and released, and samples collected and preserved in liquid nitrogen for our lab team at Sokoine University, who will screen the samples for the presence of viral RNA. Many of the bats had already migrated to other areas (seasonal migration is common for fruit bats), so Team Popo learned from local villagers about the best times of year to return the the Magombelema area when bats are most abundant for future capture and sampling work.

HALI's VISHA project is working to understand viral sharing between animals like bats and non-human primates and people in the Udzungwa area along with potential risk factors associated with viral spillover and spread.

Tent setup on arrival

The team at Magombelema cave site

The team makes their way up the cave to take a peak inside

Maneuvering through an opening leading into one of 12 chambers that make up Magombelema cave

A mist netted bat with a view of Udekwa in the background

The team untangling trapped bats before collecting samples

Some of the different bat species we came across

The majority were megabats.

The cave opening as seen from a distance. Crop fields can also be seen next to the cave.

- David Wolking

The HALI field team led by Drs. Zikankuba Sijali and Goodluck Paul was in Dar es Salaam all weekend identifying fruit bat colonies near urban areas as part of the PREDICT's wildlife disease surveillance project. Using mist nets (special nets designed to safely capture bats) suspended from roosting sites high in the trees, the team trapped three different species of bats at multiple sites, and took samples to help PREDICT understand what viruses these ancient mammals carry that might pose a potential health threat to humans. All of the bats were released after sampling, to continue their critical ecological role as pollinators. Our staff scientist Dr. Liz Vanwormer captured the team in action in these great pictures.

Fruit bats captured in a mist net at dawn in Dar es Salaam.

HALI team members prepare to collect samples from a fruit bat captured in Dar es Salaam.

Wearing protective gloves, a HALI team member holds a captured fruit bat before sampling.

Thousands of fruit bats live in the tall trees surrounding this housing compound in urban Dar es Salaam. The close proximity of people and wildlife makes this a key interface to evaluate for the risk of zoonotic disease transmission.

A mist net hovers high above an urban housing compound. One of the challenges the HALI team faces in the field is reaching the heights where fruit bats leave and return to their roosts.

Fruit bats taking flight at dusk. Fruit bats play an essential role in pollination of many plant species, and it's easy to be awed by thousands of them flying together toward their feeding areas.

HALI Project

The Health for Animals and Livelihood Improvement (HALI) project works with local stakeholders to investigate health at the human-animal-environment interface in Tanzania.

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HALI is supported by grant funding, awards, and through the contributions of our network of dedicated volunteers and team members. To ensure sustainability of our programs and to keep our talented teams and activities funded, HALI relies upon philanthropic support from private donors. Please consider supporting the HALI project by visiting our donation center at the UC Davis Wildlife Health Center.